package FileUpload.servlet;

 import java.io.BufferedReader;

 import java.io.File;

 import java.io.FileReader;

 import java.io.IOException;

 import java.io.PrintWriter;

 import javax.servlet.ServletException;

 import javax.servlet.annotation.*;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import javax.servlet.http.Part;

 /**

  * Servlet implementation class FileUploadServlet

  */

 //上传文件被保存的路径

 @MultipartConfig(

         location="E:\\eclipse\\workspace\\TestAceEditor\\FileUpload"

         )

 @WebServlet(urlPatterns={"/fileUpload"})

 public class FileUploadServlet extends HttpServlet {

     private static final long serialVersionUID = 1L;

     //private static final Log log = LogFactory.getLog(UploadFileAction.class);

     //private String fileNameExtractorRegex = "filename=\".+\"";

     /**

      * @see HttpServlet#HttpServlet()

      */

     public FileUploadServlet() {

         super();

         // TODO Auto-generated constructor stub

     }

     //获得指定文件的内容

     private String getFileContent(String fileName){

         File file = new File(fileName);

         BufferedReader reader = null;

         String ans = "";

         try{

             reader = new BufferedReader(new FileReader(file));

             String tmpString = null;

             //一行一行的读取文件里面的内容

             while((tmpString = reader.readLine()) != null){

                 ans += tmpString + "\n";//保存在ans里面

             }

         }catch(IOException e){

             e.printStackTrace();

         }finally{

             if(reader != null)

             {

                 try{

                     reader.close();

                 }catch(IOException e1){

                     e1.printStackTrace();

                 }

             }

         }

         //返回获得的文件内容

         return ans;

     }

     //获得上传文件的文件名

     private String getFilename(Part part){

         if(part == null){

             return null;

         }

         //获得文件名的方法是根据一本书上的代码来的，忘记书名了，以后补上

         String contentDispositionHeader = part.getHeader("content-disposition");

         String fileName = null;

         String[] elements = contentDispositionHeader.split(";");

         for(String element:elements){

             if(element.trim().startsWith("filename")){

                 fileName = element.substring(element.indexOf('=') + 1).trim().replace("\"", "");

                 break;

             }

         }

         fileName = fileName.substring(fileName.lastIndexOf('\\') + 1);

 //        Pattern pattern = Pattern.compile(fileNameExtractorRegex);

 //        Matcher matcher = pattern.matcher(contentDispositionHeader);

 //        String fileName = null;

 //        if(matcher.find()){

 //            fileName = matcher.group();

 //            fileName = fileName.substring(10, fileName.length()-1);

 //        }  

         return fileName;

     }

     /**

      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

      */

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         // TODO Auto-generated method stub

         request.getRequestDispatcher("fileUpload.jsp").forward(request, response);

     }

     /**

      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

      */

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         // TODO Auto-generated method stub

         //set the encoding

         request.setCharacterEncoding("UTF-8");

         //请求（form中为file类型的输入框的名字为filename）发送过来时，使用getPart()方法取得Part实现对象

         Part part = request.getPart("filename");

         String fileName = getFilename(part);

         if(fileName != null && !fileName.isEmpty()){

             part.write(fileName);

         }

         //从指定文件路径获得文件内容

         String filePath = "E:\\eclipse\\workspace\\TestAceEditor\\FileUpload" + "\\" + fileName;

         String fileContent = getFileContent(filePath);

         //write to browser

 //        response.setContentType("text/html");

 //        PrintWriter writer = response.getWriter();

 //        writer.print("<br/>Uploaded file name: "+ fileName);

 //        writer.print("<br/>Size: "+part.getSize());

 //

 //        String author = request.getParameter("author");

 //        writer.print("<br/>Author: "+author);

         //设置属性，在jsp文件中可以使用EL获得fileContent对象里的内容

         request.setAttribute("fileContent", fileContent);

         request.getRequestDispatcher("fileUpload.jsp").forward(request, response);

     }

 }

 <%@ page language="java" contentType="text/html; charset=UTF-8"

     pageEncoding="UTF-8"%>

 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

 <html>

 <head>

 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

 <title>fileupload</title>

 <style type="text/css" media="screen">

     body {

         overflow: hidden;

     }

     #editor {

         margin: 0;

         position: absolute;

         top: 130px;

         bottom: 0;

         left: 0;

         right: 0;

     }

  </style>

 </head>

 <body>

 <div style="margin:left">

 <h1>editor my code</h1>

 </div>

 <div style="background:#BFEFFF">

 <form action="fileUpload" enctype="multipart/form-data" method="post">

 Select file to show <input type="file" name="filename"/>

 <input type="submit" value="Show"/>

 </form>

 </div>

 <div id="editor">

 <!-- show the content in the uploading file -->

 ${fileContent}

 </div>

 </body>

 </html>